Spatiotemporal Information Processing No.3 3 components of Virtual Reality-2 Display System Kazuhiko HAMAMOTO Dept. of Information Media Technology, School of Information and Telecommunication Eng., Tokai University, Japan

Today’s Contents  Perception of depth and distance The crystalline lens Binocular convergence Binocular parallax  Head Mounted Display  Large sized screen Stereoscopy for large sized screen  Anaglyph  Polarization method  Active method  Immersive Virtual Environment  3D display for naked eyes

The relationship among 3 components (review) Person real spacevirtual space Simulation system Display system Sensing system computer

Visual Display  Role of visual display To give user visual presence 3 components of visual presence  a wide field of vision  Perception of depth and distance  High resolution  Discovery of the visual area in brain : 1855  Theory of 3 primary colors : 1800

Mechanism of perception of depth and distance  Less than 2m Accommodation of the crystalline lens  Less than 20m Binocular convergence  Less than 100m Binocular parallax = “stereopsis”  Less than 200m Motion parallax

Accommodation of the lens and the visual angle  Accommodation of the lens Focus adjustment of retinal image Ciliary muscle and elasticity of the lens adjust the thickness of the lens Distance is estimated from the muscle’s tension Not so good precision and effective in 2m area  The visual angle Defined by the distance and size of an object Related to the size of retinal image Important factor as well as parallax and convergence Eyeball The visual angle object Retinal image The lens

Mechanism of the binocular convergence  The binocular convergence Eyeballs’ motion which want to catch an object in the central fovea  Optical angle Angle of crossing point of the lines of sight  The distance between eye and an object is estimated from optical angle and the pupil distance

Mechanism of binocular parallax  Different perspective view in left eye and right eye caused by the pupil distance  The views are compared in visual area in brain and perception of depth is felt  The main function is to feel uneven surface of an object Retina image Left Right

Head Mounted Display (HMD)  Human vision : always ahead → a front view is always provided  Display in front of eye and tracker Ultimate display VPL Inc., Eyephone

Features of HMD  Advantages 3D image is available High immersive impression No need of wide area  Disadvantages Weight Resolution Design of optical lens Private use

Stereoscopy by HMD  Contradiction of depth information between optical angle and crystalline lens → not real view, like miniature model  Transform of distance to display by convex lens The display position is about 2m from eye, where the lens doesn’t work ( called virtual plane ). No change in visual angle Only optical angle, parallax and visual angle determine the depth.

Current status and future of HMD  Current status In the “Winter” Immersive type is mainly provided Key technologies  High resolution and small LCD  Significant modification of optical system  Future Use in the field of Mixed Reality ？ CEATEC2010 NTT docomo AR walker

Large sized screen (single screen type) Arch type screenSlope type screen Contrivances for high immersive impression Hemisphere type screen

Stereoscopy for large sized screen  Use of binocular parallax anaglyph polarization method active method

 Anaglyph Images are presented to each eye in red and blue Left eye ： red filter →only blue image reaches Right eye ： blue filter → only red image reaches Lack of color information Stereoscopy for large sized screen

鏡面反射スクリーン Stereoscopy for large sized screen Polarization method Silver screen Left image Right image Polarization filter Vertical direction Horizontal direction Polarization filter (horizontal) Polarization filter (vertical) Can see left image only Can see right image only

 Disadvantages of polarization method Screen which doesn’t change the axis of polarization is needed  Silver screen, etc.  It is usually expensive than usual 2 projectors are needed Stereoscopy for large sized screen

 Linear polarization Oscillation direction of the light is constant 2 kinds of polarization filter are used, Vertical and horizontal direction. If position of head leans, cross-talk occurs. IMAX DIGITAL uses this method.  Circular polarization The light transmits circularly along traveling direction Left image and right image are separated by the circular direction. Not depend on neck angle Warner mycal uses “RealD”. RealD=circular polarization +active Stereoscopy for large sized screen

 Active method Showing image for right eye and image for left eye alternately by one projector. Use of special glasses with LCD shutter, by which each of images can be presented to a corresponding eye only TOHO CINEMAS, Kadokawa Cinema complex and 3 TV for consumer use this method XpanD Stereoscopy for large sized screen

One Projector A glasses with LCD shutters Active Shutter Method

Left image Afterimage of right image Right image Active Shutter Method

Right image Active Shutter Method

Left image Active Shutter Method

Right image Active Shutter Method

Left image Active Shutter Method

Right image Active Shutter Method

Left image Active Shutter Method

Right image Active Shutter Method

 Features of Active method Advantage  Very few cross-talk, approximately ideal stereoscopy  Not depend on screen material disadvantage  The glass is more expensive than one for polarization method  Scene becomes dark because one side always closes. Stereoscopy for large sized screen

Problem of current 3D - 1  3D from only “binocular parallax”  Contradiction to other visual information  Information by crystalline lens and optical angle  Contradiction to other senses of organ  The senses of balance and sound  Former experiences

For example, 3D theatre Taking 3D picture Cross point Screen position Theatre Seats correspond to camera position The best seats Distance between seat and screen depends on the seat. 6.5cm (stereo base)

Problem of current 3D - 2  Technical problem Cross-talk  The opposite eye’s image leaks out Always one side (active method)  Not natural scene presentation  The brightness becomes half.

 Immersive display Person is surrounded by multiple 3D screens. Only virtual space is presented to a person. Real space cannot be perceived. The display has “Tracker”. Person can be immersed in virtual space. “Simulation sickness” due to delay of change of virtual environment to person’s motion, etc. Stereoscopy for large sized screen

CAVE  1 user wears “tracker”. The user is called “driver”.  The binocular parallax images are presented for the driver.  Driver can see “complete” virtual space.

Display system Example of immersive display CABIN (5 screens CAVE at the Univ. of Tokyo) COSMOS (6 screens CAVE at Gifu VR center) TEELeX (5.5 screens CAVE at National Institute of Multimedia Education)

Stereoscopy for CAVE  User see images projected from rear side by active method usually.  Difference from HMD, or large sized single screen The position of Virtual plane and real plane are different. The position of Virtual plane and real plane are the same. Width field of view without any motion User can see user own body.

HoloStage （ Tokai Univ. ）  5.46m wide×3m hight  1920×1200 ， 6600 ル lumen  10 projectors are used  4K stereo in one screen  High resolution (1-2mm/pixel)  Optical tracking  7.1ch ， and 3D stereo sound system

3D LCD for naked eyes  Parallax barrier is structured by switching LC  Parallax barrier can control of the direction of the light for each of left eye and right eye  TFT LCD can present a image generated specially from left image and right image.  When ordinary 2D image is presented, parallax barrier can be turned off. SHARP : 3D LCD （ parallax barrier method ）

 Small panel for mobile, especially, game  LCD + 3D LCD switch panel + touch panel  Integration of 3D LCD switch panel and Touch panel. The increment of thickness of the panel is suppressed. In 3D & VR exhibition D LCD for naked eyes SHARP : 3D LCD （ parallax barrier method ）